This invention relates generally to cable racks which are used to support heavy cables and splice cases in manholes and controlled environmental vaults. More particularly, the present invention relates to various devices and techniques for bonding the cable racks to a common ground point.
Cable racks to which the invention relates are commonly installed in manholes and controlled environmental vaults. The cable racks conventionally are elongated metal members which have a row of generally T-shaped slots. The racks are vertically oriented and bolted to concrete walls by lag bolts or other conventional fastening means. Hooks for supporting heavy cables, splice cases and other products are removeably installed upon insertion in the cable rack slots.
The cable rack environment is frequently subject to ground water contamination as well as significant quantities of corrosive compounds. Salt and other corrosive chemicals are also found in the ground water. Consequently, the ground water functions as an electrolytic solution relative to the racks. If the metal hardware of the cable racking in the controlled environmental vaults or manholes is not at the same electrical potential, the electrolytic system accelerates corrosion of the cable racks.
The tendency of the metal cable racks to corrode as a result of their presence in an electrolytic system, has dictated the common practice of connecting the cable racks to a common ground point. While the conductor connection with a common ground point is accomplished in a wide variety of on-site expediently devised techniques, the most common technique is simply to clamp the ground conductor between a pair of washers secured to a lag bolt which mounts the cable rack.